Uncertain. Moș and its feminine counterpart moașă (“midwife; old woman”) (which appears to be older) are often considered substratum words related to Albanian moshë or derived from it, but can also possibly be from Latin annōsus (“aged, old, full of years”) with a loss of the initial vowel as in some other cases (compare mătușă, noaten, nămaie), and the -ș- sound formed as with coș. The change of -n- to -m- is more unusual, but has other instances as well (compare măgar, miel, miță). Its presence in all Eastern Romance languages (compare Aromanian mosh, moashi) and the addition of the prefix stră- also indicates that it is an old word and probably from a Latin source. 
moș m (plural moși)
- an old man
- ^ Alexandru Ciorănescu, Dicționarul etimologic român, s.v. "moș" (Tenerife: Universidad de la Laguna, 1958-1966).
- ^ Dicționarul explicativ al limbii române, ediția a II-a, ed. Academia Română, Institutul de Lingvistică Iorgu Iordan, s.v. "moș" (Univers Enciclopedic, 1998).
- ^ Orel, Vladimir (1998) , “moș”, in Albanian Etymological Dictionary, Leiden, Boston, Cologne: Brill, →ISBN, page 274
- ^ Romanian Explanatory Dictionary